This invention relates generally to an electrical connector and, more particularly, to a conductive elastomer connector and to the method of making the same.
With the advent of micro displays being used in digital computers and wrist watches, the problem of interconnecting the display panels to the logic circuits has become acute because of the very small spaces involved in such applications. The use of conductive elastomer electrical connectors for interconnecting the display panels to the logic curcuits is well known in the art. Reference is made to U.S. Pat. No. 3,648,002 to DuRocher, which discloses a conductive elastomer connector in which conductive elastomer pads are mounted in openings in a nonconductive elastomer substrate. The upper and lower surfaces of the pads are flush with the upper and lower surfaces of the substrate. The pads are formed of a resiliently compressible, electrically nonconductive elastomer having discrete, electrically conductive particles dispersed therethrough. The particles may be carbon black or metal, such as gold or silver, or a combination of the same. The preferred elastomer is silicone rubber because of its long term stability and relatively low compression set. The conductive particles are responsive to compression of the pads to establish electrically conductive paths through the pads. As will be appreciated, since the surfaces of the pads are flush with the upper and lower surfaces of the nonconductive elastomer substrate, compression of the substrate is required in order to compress the pads and thus render them electrically conductive. This arrangement leads to the requirement of relatively high compression forces in order to provide electrical connection between the electronic devices being interconnected by the aforementioned conductive elastomer connector. Furthermore, such connector does not permit as high density pattern of electrical paths as is required for some applications. It is the purpose of the present invention to provide a conductive elastomer connector which does not require compression of the nonconductive substrate to render the conductor filled pads electrically conductive and will permit higher density packaging than the prior art connector described hereinbefore.
The term "conductive elastomer" utilized in this specification and the claims appended hereto is intended to mean a compressible nonconductive elastomer filled with conductive particles, which becomes electrically conductive when compressed as described hereinabove and disclosed in detail in the aforementioned DuRocher patent. The term "conductive elastomer" is also intended to include an elastomer sufficiently loaded with conductive particles that it is electrically conductive even without compression.